Speed and precision paired with high holding forces

Rexroth teamed up with Berlin-based Bekum Maschinenfabriken GmbH to develop a hybrid drive for the closing system of blow molding machines. The drive not only meets dynamic axis requirements, but also the need for fast, stroke-independent buildup of force at closure and contemporary (low) energy consumption and noise levels.

The innovative hybrid drive leverages the benefits of hydraulic and electric drives to maintain applied forces over extended periods and gently buffer fast changes in direction. It is also efficient, precise, and minimizes noise emissions. To develop this system, which does without a classic hydraulic setup with tank and displacer unit, both partners had to break new ground.

A hydraulic gearbox was fitted between the electric drive and linear axis for the closing system of blow molding machines and is used to convert rotary to linear movement and provide for targeted switching between rapid and power strokes. This considerably reduces the loads for the drive side and the ball screw drive. A locking function in the hydraulic gearbox enables the closing force to be held without drive torque, similar to a classic hydraulic machine.

Internal tests and initial field applications confirm the everyday suitability of the new development.

The hybrid drive can also be used for closing systems involving other applications, such as presses and injection molding machines. This innovative, customized solution is just one example of the many years of experience Rexroth has gained as an engineering partner in development projects.